(1) Field of the Invention
The present invention relates to a massage roller for exercise or fitness, and more particularly to a massage roller having an interchangeable shell.
(2) Description of the Prior Art
A conventional massage roller (also known as a yoga roller or a foam roller) is adapted for exercise or fitness. Generally, the massage roller is composed of a rigid core member and a soft shell which is softer than the core member. The core member is usually made of non-expanded plastic. The soft shell is usually made of foam material such as expanded polyethylene or expanded polypropylene. Commonly, the soft shell is deposed around the outer surface of the core member; the soft shell and the core member are adhered to each other via a cohesive agent so that the soft shell would not be detached from the core member or rotate relative to the core member.
As shown in FIG. 8, another conventional detachable yoga rod structure comprises a yoga rod 51 and an outer sleeve 52. The outer sleeve 52 is merely sleeved on a smooth surface 511 of the yoga rod 51 but is not adhered to the yoga rod 51 or secured on the yoga rod 51. Thus, when a user presses on the yoga rod structure5, the outer sleeve 52 is possible to rotate relative to the yoga rod 51 and further be separated from the yoga rod 51.